The present invention relates to cordless telephones operating from base stations which are connected to conventional telephone systems. More particularly, the present invention relates to the field of cordless telephones that may operate with an effective, connection to a conventional telephone system when the cordless telephone is out of range of its base station.
There is an ongoing need for a communication system in which out of range operation for a cordless telephone can be achieved to thus eliminate the necessity for employing a cellular telephone (with the consequent cost) or the use of the telephone connection of another party.
The present invention is a cordless telephone that can place, receive or continue processing of telephone calls, whether or not the cordless telephone is in range of its home base station. When out of range of its home base station, the cordless telephone of the subject invention transmits or receives digital mode signals with a non-home base station. Those transmitted or received digital mode signals are routed in one of several possible methods between the cordless telephone and its home base station, wirelessly or by wired connection.
The home base station receives the transmitted digital mode signals from a non-home base station, translates them to analog or other digital (i.e, such as ISDN) or data signals and transmits them to a home telephone line. The home base station may also receive analog or other digital (i.e, such as ISDN) or data signals from the telephone line, translate them to digital mode signals and transmit them to the non-home base station for retransmission to the cordless telephone.
A non-home base station can wirelessly route digital mode signals to the home base station, or vice versa. The wireless routing can be direct or indirect.
Direct wireless routing has a non-home base station in wireless range of a home base station. The digital mode signals are directly exchanged between those two base stations. This means that the cordless phone is out of range of its home base station but in range of the non-home base station.
Indirect wireless routing uses additional, intervening non-home base stations. A first non-home base station is out of range of the home base station but in range of a second non-home base station. The second station is either in range of the home base station or in range of a third non-home station. If in range of the home base station, the second station acts as a wireless link from the first non-home base station to the home base station. Other intervening non-home base stations can act as additional wireless links to span the distance between the first non-home base station and the home base station.
As long as one or more non-home base stations have overlapping wireless communication ranges between the cordless phone and the home base station, the user can move freely out of range of the home base station without service interruption. More importantly, the user can conceivably avoid cellular or telephone network charges for wireless communication from the cordless phone to the home base station. The invention wireless routing can be made without devoting new wireless bandwidth to its operation. Most locations in the world have cordless phone bandwidth already segregated for that purpose apart from cellular or other uses.
For effective wireless routing, the user can strategically locate his own non-home base stations within wireless range of each other over a desired area. Or the user can depend on non-home base stations located in and operating as parts of the base stations of other invention cordless phones. A new user gets their own uniquely addressed cordless phone and home base station and installs the home base station at a desired location. That new base station has means for acting as a non-home base station for another cordless phone uniquely addressed to a different home base station. Each new home base station installation at the desired location of a new user becomes an extension of the effective wireless operating range of the invention system.
Such call processing of the invention cordless telephone through a non-home base station does not substantially affect call processing of a second telephone that can use the non-home base station as the second telephone""s home base station.
Digital mode, as used herein, describes a digital transmission and reception technology signal, i.e., TDMA, E-TDMA, narrow band CDMA, and broadband CDMA, spread spectrum, or other appropriate mode that may be transmitted on a channel. In an optional mode, the cordless telephone may employ a direct wire connection with a non-home base station for processing. The subject system allows the cordless telephone user to roam away from his home base station to the range of another base station and transmit and receive in digital mode to the other base station without interfering with the local analog operation of the other base station. This aspect of non-interference or line sharing is entirely novel to the art.
For the out of range or roaming cordless telephone, digital mode signals are exchanged by a roaming cordless telephone at a signal-separable frequency than that of the one or more cordless telephone handsets for the other base station so the signals do not interfere with each other. In one of several methods of routing transmission from a roaming cordless telephone, a received signal from the out of range cordless telephone is received by the other base station and transmitted from the other base station to the home base station for translation to analog or other appropriate signals (such as for data communications).
The digital mode signals sent by the other base station are of course transmitted on the same conventional telephone network connection (land line, wireless or other means, referred to hereafter just as xe2x80x9cland line xe2x80x9d) used by the other station for its own analog or other communications with a telephone network. The concurrent operation of the subject system and the normal operation of the other base station takes place so that the integrity of the normal operation of the other base station is at least its substantially maintained. Although complete absence of interference by line sharing would be preferable, the owner of the other base station may well accept a reduced performance of normal operation if in exchange for being part of the invention system and to share in its benefits.
In further explanation of the subject system, digital mode transmissions (and received signals as well) enter the land lines of the other base station from the other base station for handling in one of several modes of routing to the home base station. The digital mode transmissions may be received by the telephone network with unique identifier(s) indicating that the signals or packets must be directed to the home base station.
In an alternate embodiment, the other base station and its associated telephone account may be equipped with broad band communications technology, such as for DSL communications, permitting co-transmission of the digital mode signals with the normal operation of the other base station telephone line, although using some of the bandwidth of the telephone account for the other base station. In another alternate embodiment, the digital mode signals may be transmitted directly to the home base station without requiring processing by the telephone network. In one or more of these transmission (and/or receiving) methods for digital mode signals from the other base station to the home base station, the digital mode signals are delivered to the home base station.
The home base station incorporates apparatus for receiving these transmissions. in a manner such that it does not substantially impair the normal land line operation. The normal land line operation may include exchange of signals in analog or other digital (i.e., such as ISDN and the like) and data signals. Analog signals are needed for phone speaker and microphone operation. The home base station, upon receiving a digital mode signal from the roaming cordless telephone (for example, the first number of a desired telephone number that the user wants to call) moves the home base station to an off-hook state and transmits the transformed digital mode signal (now in analog or other digital (i.e, such as ISDN) form) to the telephone network for appropriate processing. Each subsequent number received from the roaming cordless telephone causes the telephone network to respond as if the cordless telephone were within its home base station range. When a dial up attempt is completed, the roaming cordless telephone receives communications signals in the reverse order, i.e., the home base station receives an analog signal from a telephone network source, the analog signal is,translated to a digital mode signal, the digital mode signal is transmitted to the other base station, the other base station transmits the non-analog signal to the roaming cordless telephone, and the roaming cordless telephone transforms the non-analog signal to an analog signal that may result in an audible or data output usable by the roaming cordless telephone holder.
These simple concepts eliminate the need for an out of range base station with a land line committed only to reception and transmission of signals from the roaming cordless handset. The prior art contains many examples of cordless telephones that switch to a cellular network when out of range of home base station. The present invention system is not one of that category.
The present invention may incorporate a feature for timing out in a standby mode for a period of time if the roaming cordless telephone moves out of range of any receptive base station, so that the user traveling in a car or other transport may not lose communication contact with the connected telephone number during a call. The out of range base station can. be a telephone with similar capabilities as that of the home base station, providing inducement for many user""s in a locality (corporate building or campus small community or other relatively compact geographical area) to install the subject cordless telephone so that they may have the benefit of out of range operation without the need to pay for a cellular network call.
It is well known that cellular network calls are many times more expensive than those from a single land line telephone. The subject system having at least one cordless telephone and two or more. base stations permits the user to place and receive calls from out of range locations where the only charges that will accrue to the user will be those that would have accrued had the user been within range of the home base station.
The frequencies for a roaming cordless telephone and that set aside for the local cordless telephone preferably operate within the broad ranges set aside for the spread spectrum technology of the 900 MHz and 2.4 GHz cordless telephones. It is well known from the cellular telephone art and the cellularxe2x80x94cordless telephone art that one of several frequencies may be programmably selected by the invention cordless telephone so that its communication frequency does not interfere with the communications of a local. base station as opposed to the home base station of the roaming cordless telephone. It is also well known in the cellular telephone art and the cellularxe2x80x94cordless telephone art that base station range sensing expedients and range to range xe2x80x9chand-offxe2x80x9d expedients presently exist for relatively simple incorporation into the subject system so a roaming cordless telephone can move out of range of one of the other base stations and automatically transfer all communication exchanges with a nearby or adjacent-range base station. Optionally, the user can be given a visual or audible signal that the roaming cordless telephone is moving out of and/or into range of another base station. Such signal will alert the user that their call may be terminated if another base station range is not at least nearby.